Ellipse guide



C. H. THOMPSON Nov. 27, 1962 ELLIPSE GUIDE 2 Sheets-Sheet 1 Filed May 13, 1960 w R m s N p. M V o u T H S w 7 R A. W. 0 u C F w {L /\/0 my 7 5 m J n k 1% 7.

ATTORNEVS Nov. 27, 1962 c. H. THOMPSON ELLIPSE GUIDE 2 Sheets-Sheet 2 Filed May 13, 1960 amid 0Q m m w mm INVENTOR.

H THOMPSON c HAR LES v fim ATTORNEYS United States This invention relates to improvements in devices for drawing geometrical figures, and more particularly to an ellipse drafting device.

A main object of the invention is to provide a novel and improved ellipse drafting device which is relatively simple in construction, which is easy to use, and which may be conveniently employed for drawing ellipses of varying sizes and proportions, using any desired type of scribing point, such as a pencil point, an ink point, or a scriber.

A further object of the invention is to provide an improved ellipse drafting device which is relatively inexpensive to manufacture, which provides a high degree of accuracy, which is easy to'adjust so that an ellipse of desired size and proportions may be scribed, which is relatively compact in size, which is light in Weight, and which is easy to store. I

A still further object of the invention is to provide an improved ellipse drafting device which is less complicated than devices for this purpose previously avail able, which is arranged so that a desired ellipse may be drawn around a specified center point, which enables a full ellipse to be drawn without requiring any change in position of the device, and which draws an ellipse which is visible at all points.

Further objects and advantages of the invention will become apparent from the following description and claim, and from the accompanying drawings, wherein:

FIGURE 1 is a perspective view of an improved ellipse drafting device constructed in accordance with the present invention.

FIGURE 2 is an enlarged top plan view of the ellipse drafting device of FIGURE 1.

FIGURE 3 is an elevational view partly in cross section of the ellipse drafting device of FIGURES 1 and 2, taken substantially on the line 33 of FIGURE 2.

FIGURE 4 is an enlarged vertical cross sectional view taken substantially on the line 44 of FIGURE 2.

FIGURE 5 is a cross sectional view taken on the line 55 of FIGURE 4.

FIGURE 6 is an enlarged vertical cross sectional view taken substantially on the line 6-6 of FIGURE 3.

FIGURE 7 is an enlarged vertical cross sectional view taken substantially on the line 7--7 of FIGURE 3.

Referring to the drawings, 11 generally designates an improved ellipse drafting device constructed in accordance with the present invention. The device 11 comprises a flat horizontal supporting body 12 which is generally rectangular in shape and which is formed with a relatively large intermediate scribing notch 13 defining a longitudinally extending main arm 14 at one side of the body 12 and respective transversely extending end arms 15 and 16 at the opposite ends of the body.

The arm 15 is formed with a longitudinally extending groove 17 which extends parallel to the longitudinally extending main arm 14. Designated at 18 is a horizontal flange which is integrally formed on the transverse arm 15 and which is spaced above and which overlies the portion thereof containing the groove 17, thus defining a slot 20. Designated at 21 is a scribing arm of substantial length which is formed at its opposite ends with the respective transversely extending arm portions 22 and 23, the arm portion 23 being received in the slot and being slidably and pivotally connected to the transversely extending end portion 15 of the horizontal supporting body 12 by the provision of a vertical rivet atent G 24 secured in the arm end portion 23 and provided with a depending stud element 25 which is slidably engaged in the groove 17, as is clearly shown in FIGURE 7.

Designated at 28 is the ellipse major diameter-determining arm, which is pivoted to the transverse end portion 16 of the main supporting body 12 at a point aligned with the groove 17, the pivotal connection comprising a bearing member 31 which depends from the arm 28 and which is secured thereto by a rivet 32, as shown in FIGURE 4, the bearing member being rotatably engaged through a flanged bearing plate element 33 provided on the arm member 16. Thus, the arm member 16 is formed With a notch 34 at its inner margin and the bearing plate 33 is secured by rivets 35 to the arm portion 16 over said notch 34, the surface of the arm portion 16 being countersunk to receive the bearing plate 33 so that said bearing plate is substantially flush with the top surface of arm portion 16, as shown in FIGURE 4. The bearing element 31 extends through a bearing opening provided in the plate member 33 said bearing element being formed with an enlarged an nular lower portion 36 which retains the bearing member against upward displacement but allows said member to rotate freely in the bearing opening 37 provided in the plate member 33, as shown in FIGURE 4.

The major diameter-determining arm 28 is formed with a T-shaped groove 38 which slidably receives the head of an inverted pivot screw 39, the screw 39 being provided with the clamping nut 40 threadedly engaged thereon. A flanged annular bearing collar 41 surrounds the screw 39 and is supported on the marginal portions on the opposite sides of the groove 38, being clamped to the arm 28 at a specified point along the groove by the tightening of the nut 40, a suitable clamping washer 42 being provided on the screw 39 between the nut 40 and the top rim of the collar member 41. The end portion of transversely extending arm member 22 is rotatably engaged with the collar member 41, being supported on the bottom flange of said collar member, shown at 44 in FIGURE 4. Thus, the scribing arm 21 is pivoted to the ellipse major diameter-determining arm 28 at a selected position along the groove 38, in accordance with the desired ellipse major diameter, as determined by a suitable scale 45 inscribed on the top surface of the arm 28 along one margin of groove 38.

As shown in FIGURES 1 and 2, the bearing plate 33 is located substantially centrally of an inwardly facing semicircular notch 46 formed in the transversely extending arm portion 16, the semicircular notch 46 defining one end of the large main notch 13 provided in the flat supporting body 12.

Secured on the longitudinally extending main portion of the scribing arm 21 is the longitudinally extending, generally channel-shaped supporting bracket 47 provided at its opposite ends with the upstanding vertical flanges 48 and 49. Designated at 50 is a longitudinally extending supporting shaft which is journaled in the upstanding flanges 48 and 49, said upstanding flanges being provided with inwardly projecting opposing pivots 51 which are rotatably received in respective pivot recesses provided therefor in the opposite ends of the shaft 50, in the manner illustrated in FIGURE 3. The pivots 51 are threadedly engaged through the flanges 48 and 49 and are secured in adjusted positions by the provision of locking nuts 52 provided thereon, as shown in FIGURE 3.

Slidably mounted on the shaft 50 is a collar member 53, said collar member being locked in a selected position on the shaft 50 by means of a locking screw 54 threadedly engaged in the collar member and being clampingly engageable with the shaft 50. Secured to the collar member 53 is the arm 55 which projects laterally from the collar member and which is formed with the downwardly Any desired scribing element may be employed in place of the inking member 60, for example, a pencil point, a scribing point, or the like.

As shown in FIGURES 1 and 2, the arm 55 is of sufficient length so that the scribing element 60 may be positioned with its point62 located on the common longitudinal axis line 63 containing the pivot point of the ellipse major diameter-determining arm 28 and the axis 7 of the groove 17.

The bracket member 47 is inscribed with a longitudinally extending minor diameter scale 65, and the collar r member 53 is provided with a depending pointer element 66 located immediately above the scale 65' to enable the collar member 53 to be set to a position along the scale 65 in accordance with the minor diameter of the desired ellipse to be drawn.

Designated at 70 is an elevating cam member comprising an elongated rod-like element formed with opposite end portions 71 and 72 which are offset from the main body of the member 70 and which are rotatably supported on a common longitudinal axis in the respective upstanding flanges 49 and 48. The shaft portion 72 is formed with the operating extension 74 which is arcuately curved and which may be manually rotated, whereby to rotate the ofiset longitudinally extending main portion of the rod-like cam 70. The ofiset intermediate main portion of said cam underlies the scriber-bearing arm 55 and may be rotated to engage and elevate same when it is desired to lift the scriber element 60 ofi the paper. Thus,

purpose of filing same withink, where an inking point is employed.

Designated at 80 is an alignment gauge member which comprises an elongated body having oppositely extending end portions 81 and 82 and a main intermediate portion 83 which is dimensioned to fit between the inwardly facing end edge portion 84 of the transverse arm 16 and the transversely extending inside edge 85 of the arm portion 15. Thus, the body 83 is slidable between the transverse edge element 84 and the transverse edge element 85 to a position wherein the end lugs 81 and 82 abut against the front longitudinal surfaces of the main supporting body 12. The guidetmember 80 is formed at its inner margin witha longitudinally extendingscale 86 which is identical to the scale 65 and which may be employed to adjust the device so that the center point of the intended ellipse coincides with a point on the alignment insert scale .86 which corresponds with the reading on the minor diameter scale 65 indicated by the pointer element '66.

As will be readily apparent, the radius of revolution set to the desired position along the major diameter scale in accordance with the major diameter of the desired ellipse to be drawn. Nut 40 is then tightened. The scriber arm clamping screw 54 is then loosened and the collar member 53 carrying the member 55 is moved along the shaft until the pointer element 66 is positioned over the desired minordiameter value on the minor diameter scale 65. The clamping screw 54 isthen tightened. The arm is then elevated by rotating the arcuate extension 74 of cam member 70, allowing the scriber element to be filled with ink, if an inking point is employed. The alignment guide member 80 is then inserted between the edge 84 and the vertical transverse surface 85 with the lugs 81 and 82 abutting the outer longitudinal vertical surfaces at the front of the device, as above described, and the device is then moved to align the scale 86 of the member 80 with the major diameter center line 63 of the intended eilipse. The device is then movedalong the line 63 to a position wherein the center point of the intended ellipse coincides with a point on the alignment insert scale 86 which corresponds with the reading on the minor diameter scale indicated by the pointer 66. The alignment insert element 80 is then removed and the scriber arm member 55 is lowered by rotating the rod-like cam member to the position shown in FIGURE 6, wherein the scribing element 60 has its point 62 in engagement with the paper. The desired ellipse is then drawn by rotating the arm 28 around its pivot bearing axis at 31, employing the nut 40 as a handle knob. After the desired ellipse has been drawn, the point 62 may be lifted ofi the paper by means of the elevating cam member 70, in the manner previously described.

In addition to the exact major diameter selecting scale 45, an isometric scale 95 may be provided on the major diameter adjustment arm 28. Thus, the isometric scale 95 may he provided on the margin of the groove 38 opposite the exact major diameter adjustment scale 45,

as shown in FIGURES 1 and 2.

Whilea specific embodiment of an improved ellipse drafting device has been disclosed in the foregoing description, it willbe understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope major diameter-determining arm, a scribing arm, means rotatably connecting one end of said scribing arm to said bearing element, theother end arm being formed with a groove aligned with the pivot 'point of said major diameterdetermining arm, a depending pin element on the other end of said scribing arm pivotally and slidably engaged in ingsaid scribing element to said supporting shaft for ad-. ustable securement alongsa'id minor' diameter scale, a Y liftmg cam rod journaled on said scribing arm parallel to said supporting shaft, said cam rod being provided with an offset portionengageable with said scribing element to elevate same responsive to rotation of said cam rod, an insert member having transverse end edges slidably engageable with theinner end edges of said transversely ex- 7 tending endtarms and fitting in said scribing notch to ex- I tend parallel to said supporting shaft, and a marginal scale on the inner longitudinaledge portion of said insert memher simiiar to and in transverse registry with said minor diameter scale.

References Cited in the file of this patent UNITED STATES PATENTS Knapp May 10, 1887 Carlton June 16, 1903 Germany Sept. 6, 1956 

